Mechanical devices intended for manipulation of biological cells and other small particles and having structural elements with dimensions ranging from tens of micrometers (the dimensions of biological cells) to nanometers (the dimensions of some biological macromolecules) have been described. For example, U.S. Pat. No. 5,928,880, U.S. Pat. No. 5,866,345, U.S. Pat. No. 5,744,366, U.S. Pat. No. 5,486,335, and U.S. Pat. No. 5,427,946 describe devices for handling cells and biological molecules. PCT Application Publication number WO 03/008931 describes a microstructure for particle and cell separation, identification, sorting, and manipulation.
U.S. Pat. No. 7,993,908 describes a microscale apparatus for separating cells and other particles based on their size. The apparatus described in that patent includes a stepped separation element interposed between two regions of a void formed by a cover and body, and separation of particles within the apparatus is governed by the ability of particles initially present in one region to traverse the stepped separation element to arrive at the other region. The subject matter disclosed herein is considered an improvement upon this apparatus.
The subject matter disclosed herein can be used to segregate and manipulate biological cells, organelles, cell conglomerates, and other particles from mixed populations of particles or cells.